1)
Who was going?
1.
Rashi: Hadad'ezer.
2)
What is the meaning of "Lehashiv Yado"?
1.
Rashi citing Targum Yonasan: He went to widen his border. Radak - he took from Yisrael.
2.
Malbim: Refer to 8:3:3:2.
3)
Why does it say here "Lehashiv Yado", and in Divrei ha'Yamim I, 18:3 it says "Lehatziv Yado"?
1.
Radak: Both of these mean the same. Initially Hadad'ezer helped Yisrael, and now he took from their land. This is why David said (Tehilim 60:3-4) "Elokim Zenachtanu Peratztanu